The identification, diagnosis, and effective management of psychiatric symptoms in Alzheimer's Disease (AD) are critical to reduce the cost of health care, to increase practitioner efficiency and to improve the quality of life for AD patients and their caregivers. Until research finds a means of treating AD with curative measures, symptoms such as delusions and hallucinations must be aggressively identified, diagnosed, and managed. Although recent research has shown a high prevalence of psychosis in AD and has implicated a worse prognosis for those AD patients with psychosis, the risk factors for and underlying mechanisms of psychosis in AD are poorly understood. The proposed project will be the first study to prospectively investigate the neuropsychologic factors associated with psychosis in AD. With the aim of exploring the heterogeneity of behavioral presentation and course in AD, the proposed studies are designed to prospectively compare the neuropsychological performances of AD patients who develop psychosis with AD patients who do not develop psychosis. Furthermore, the current proposal will retrospectively analyze the neuropsychological performances of AD patients currently enrolled in the research centers at UCSD who are identified as having psychosis.